{"id":"CVE-2023-53635","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: conntrack: fix wrong ct->timeout value\n\n(struct nf_conn)->timeout is an interval before the conntrack\nconfirmed","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: conntrack: fix wrong ct->timeout value\n\n(struct nf_conn)->timeout is an interval before the conntrack\nconfirmed.  After confirmed, it becomes a timestamp.\n\nI…","severity":"high","cvss":8.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.4, < 6.1.28","linux_kernel >= 6.2, < 6.2.15","linux_kernel >= 6.3, < 6.3.2"],"patched":["linux_kernel 6.3.2"],"published":"2025-10-07","updated":"2026-10-15","sourceUpdated":"2026-10-15T22:17:44.927","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2023-53635","references":[{"url":"https://git.kernel.org/stable/c/73db1b8f2bb6725b7391e85aab41fdf592b3c0c1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/80c5ba0078e20d926d11d0778f9a43902664ebf0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f612ae1ab4793701caf39386fb3b7f4b3ef44e48","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ff5e4ac8dd7be7f1faba955c5779a68571eeb0f8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00435,"epssPercentile":0.37574,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-15T21:36:08.236702Z"},"ingestedAt":"2026-10-15T22:48:25.413Z","slug":"CVE-2023-53635","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: conntrack: fix wrong ct->timeout value\n\n(struct nf_conn)->timeout is an interval before the conntrack\nconfirmed.  After confirmed, it becomes a timestamp.\n\nIt is observed that timeout of an unconfirmed conntrack:\n- Set by calling ctnetlink_change_timeout(). As a result,\n  `nfct_time_stamp` was wrongly added to `ct->timeout` twice.\n- Get by calling ctnetlink_dump_timeout(). As a result,\n  `nfct_time_stamp` was wrongly subtracted.\n\nCall Trace:\n <TASK>\n dump_stack_lvl\n ctnetlink_dump_timeout\n __ctnetlink_glue_build\n ctnetlink_glue_build\n __nfqnl_enqueue_packet\n nf_queue\n nf_hook_slow\n ip_mc_output\n ? __pfx_ip_finish_output\n ip_send_skb\n ? __pfx_dst_output\n udp_send_skb\n udp_sendmsg\n ? __pfx_ip_generic_getfrag\n sock_sendmsg\n\nSeparate the 2 cases in:\n- Setting `ct->timeout` in __nf_ct_set_timeout().\n- Getting `ct->timeout` in ctnetlink_dump_timeout().\n\nPablo appends:\n\nUpdate ctnetlink to set up the timeout _after_ the IPS_CONFIRMED flag is\nset on, otherwise conntrack creation via ctnetlink breaks.\n\nNote that the problem described in this patch occurs since the\nintroduction of the nfnetlink_queue conntrack support, select a\nsufficiently old Fixes: tag for -stable kernel to pick up this fix.\n\n## Affected\n\n- `linux_kernel >= 4.4, < 6.1.28`\n- `linux_kernel >= 6.2, < 6.2.15`\n- `linux_kernel >= 6.3, < 6.3.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.3.2`","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}